It is common in offices, and other environments where computers are used, to have reasonably intense light from overhead lighting fixtures and windows, in order to sufficiently illuminate an office. Due to the intensity of this light, and also due to the location of overhead lighting fixtures and windows, the light is often perceived as glare on a computer monitor screen. This glare can make it difficult, if not impossible, to see the computer monitor screen properly. It is, therefore, necessary to preclude as much of this light as possible from reaching the computer monitor screen in such a manner that it is reflected off the screen as glare.
In many instances, it may be possible to close curtains or blinds over a window in order to block much of the glare-causing emanating from a window; however, this reduces the amount of ambient light in the room, which might be unacceptable. It is generally not possible to block out the light from overhead lighting fixtures, but it is possible to turn off the overhead lights. However, even this step is often unacceptable.